1. Technical Field
The present invention relates generally to a hand operated puller for moving sheet material from one place to another. It is especially adapted for moving sheet metal stock off of a coil to a stamping machine.
Sheet metal is delivered to tool and die factories on a coil similar to a roll of paper towels. It is necessary for the workers to unroll the sheet metal and feed it into the stamping machine so that parts can be stamped from the metal. Workers currently use gloves or "C-clamps" to pull the metal stock so that it unwinds from the roll and is fed into the stamping machine. This is not only a difficult task, but many workers sustain hand injuries from handling the metal because the metal has relatively sharp edges and may have sharp spurs along the edges or in the sheet itself. It requires a considerable amount of effort to pull the metal from the spool because of the weight of and lack of flexibility in the metal. Workers are sometimes injured even when they use gloves, as sharp protusions of the metal can penetrate many types of gloves if the protrusion is sharp enough. The "C-clamps" take time to apply to the metal and remove once the metal is placed in the stamping machine. Often, the "C-clamps" must be applied to the metal more than once to pull the metal to the desired location. This increases the chance of injury to the worker.
2. Prior Art
U.S. Pat. No. 1,917,663 to Porter, issued on Jul. 11, 1933, discloses a gripper for gripping and holding a binder for packages. The binder can be either a steel strap or wire. The gripper basically consists of a stationary foot over which the binder passes. The moveable member of the gripper is a wedge shaped gripper block with teeth that engage the binder. The gripper block is mounted on an eccentric portion of a shaft which is attached to an operating handle. The eccentric portion of the shaft extends through an elongated hole in the block. In this way, rotation of the handle either lowers or raises the gripper block into or out of engagement with the binder. In effect, the Porter gripper is used to hold the binder material in tension so that it can be connected together to bundle or bind packages or groups of packages.
U.S. Pat. No. 3,284,049 to Haraden, issued on Nov. 8, 1966, discloses a feed wheel drive mechanism for strapping tools. It shows the use of a feed wheel which is mounted on an eccentric portion of a shaft. When the shaft is rotated it raises or lowers the feed wheel out of or into contact with the strap. A driving pawl turns the feed wheel to bring it into contact with the strap. A holding pawl is utilized to hold the strap in position. After releasing the driving pawl, the handle can be rotated to move the feed wheel out of contact with the strap. The Haraden strapping tool also is to pull and tension binder straps and, by use of cranks and levers, tension the binder strap, position the future ends of the binder strap relative to each other, and seals the ends together to bundle or bind packages.
Both of the Porter and Haraden tools, while capable of gripping relatively lightweight binding material, are for package binding, and are not designed or suitable for feeding relatively heavyweight sheet stock to an industrial stamping machine. Neither the Porter nor the Haraden devices can be used to pull metal off of rolls. Accordingly, it can be seen that a device is needed for pulling the metal from the roll to the stamping machine that would reduce the number of injuries to workers and to make the task easier. It would be desirable that this device be hand operated rather than motor driven in order to keep the cost lower, the technology simple and have fewer parts so as to increase reliability. It is to those goals and others which will become apparent that the present invention is directed.